Distillation of tar



3 Sheets-Sheet 1 VFiled. June 24 NEY v b l I .12. ...IN .Jl-f.-. r n u n n u N\l n u n u n n I- BY? I A AT1-on May 15, 1934 s. Ff. MILLER 1,958,440

DISTILLATION OF TAR Filed June 24, 1933 3 Sheecs-Sheei;4 2

INVENTOR S17/.ar H #7i/ler am M9 ATTORNEY May l5, 1934. s. P. MILLER DISTILLATIONOF T AR 3 Sheets-Sheet 3 Filed June 24, 1933 Patented May 15, 1934 UNITED STATES f DISTILLATION OF TAR Stuart Pal-melee Miller, Englewood, N. J., as-

signer to The Barrett Company, New York, N. Y., a corporation of New Jersey Application yJune 24, 1933, Serial No. 677,350

` In Canada May 17, 1929 22 claims. (Cranz- 30.)

This invention relates tothe operation of a coal distillation plant and especially is directed to a method for the distillation of tar, tarry oil, or pitch at such a plant. l.

Although the invention is applicable to coal distillation plants in general, such as gas retort plants, etc., it will be described in particular with relation to the operation ofA a by-product cokev oven plant since this is a Widely used type of coal distillation plant.

In the ordinary operation of a by-product coke oven plant, gases resulting from the distillation or carbonization of coal are drawn ofi fromthe,

individual ovens of the plant at temperatures ranging between 550 and-850 C. These hot gases, normally termed foulcoke oven gases are composed of permanent gases such as hydrogen and methane, aqueous vapors, and especially organic oil vapors, as well as solid particles of coke, coal, carbon, and possibly other solid matter.

Ordinarily the gases from individual ovens pass through short air-cooled uptake pipes andgoosenecks to a collecting main. The uptake pipes and goose-necks generally are uninsulated and the gases in passing through them are cooled to around 300 to 400 C./entering the collecting main at about this temperature. A single collecting main may receive gases from as many as sixty or more ovens. In the collecing main, which also is uninsulated, and ordinarily in the goosenecks, the gases are rapidly cooled by spraying copious quantities of cooling liquid into them. This cooling is not uniform as a rule but is effected by direct contact with a liquid at a much lower r temperature than ihe gases and results in the separation from the gases of a heavy tar that is by no means in equilibrium with the gases with respect to condensable constituents. The Ycooling liquid customarily employed is the ammonia liquor resulting from a subsequent cooling of the gases and in some cases this is supplemented with tar to more adequately flush the collecting main and prevent the accumulation offpitch therein. .This cooling liquid generally is supplied in such r amount that its temperalure is not raised above 80 or 85 C. and the cooling treatment otherwise is conducted in such a manner that the average gas temperature is lowered to around 150 C. or

below in the collecting main. The gases at this temperature are passed through a cross-over main or suction main to a cooler. In the passage of the gases through this cross-over main their temperaturel is usually lowered to around 80 C. and they enter the cooler at about thisA temperature. This cooler may be a direct or inrever, they generally are collected together 'as a directl type wherein the gases are cooled down to about C. and in many cases to around 25 Lto'35 C. and in which the tar, ammoniav liquor, and any other condensable constituents are condensedfrom the gases. The term condensable constituents -as used inA the iart covers those constituents that condense out from the gases anddoes'not ordinarily include benzol or light oil which mustbe removed from the gases by an absorption liquid, although small quantities of such constituents may be removed vfrom the gases along with and absorbed by the tar.

The gases are drawn from the ovens through this cooling equipment by means of anexhauster usually located beyond the cooler. 'Commonly a 70 tar extractor also is provided through which the gases vare passed ordinarily after they leave the cooler and before they are treated for the recovery of ammonia and light oil.

In each of the coolingsteps hydrocarbon vapors are condensed and solid matter carried by the gases is to some extent removed. The solid matter entrained in the gases as they leave the coke ovens is,` present in exceedingly nely divided form so that it is not readily removed in its entirety but 80 remains in the gases until the size of the particles has been increased by condensation of hydrocarbon liquids thereon and particles of tar have been formed. Even these tar-particles, however, 4are extremely persistent and are removed only after passage of the gases through the cooler, exhauster, and tar extractor. Thus it will-be seen that in the ordinary operation of a coke-oven battery,.tar is recovered from the collector main, :the cross-over main, the cooler, the exhauster,

and the tar extractor.

These tar products may vary in composition to some extent, depending upon the temperature at which they are separated from the gases. Howsingle tar product along with the ammonia liquor condensed from the gases or employed for spraying the gases in the collector main and goosenecks and the single total tar product is decanted from this ammonia liquor and collected as raw tar.Y It is this product ,containing around 2% of Water that is the raw coal tar of `commerce. From it the dry or dehydrated tar, the semi-pitches, and pitches are preparedby distillation `to varying degree. A I

The coal-tar product, raw or dehydrated; is ordinarly shipped from the coke-oven plant to a tar distillation plant for distillation and separation of oils and production of refined tars and pitches of varying qualities,

In accordance with the present process, tar is treated for the production of commercial oil and Various constituents of hot coal gas by conducting the fresh gas from the ovens through a series of coolers and cooling the gas in successive steps in order to successively condense and remove the 4various fractions. Such processes have involved the counterow of oil constituents in contact with the coal gas so as to effect a rectification of the oils and fractional condensation of the various oil fractions from the gas. The relativelyl small quantities of `tar constituents present in the gas from a coal distillation plant, however, are not conducive to a sharp fractionation and, as already mentioned, the presence of the particles of 'solid liquid material in the gases and the exceeding neness of their dispersion constitute an added difliculty. Hence such processes have not proven satisfactory commercially. It also has been proposed in the past to add tar to the collector main of a coke oven plant @d to distill the tar as a body thereof or4 as a flowing stream in the collector main doing away entirely with cooling sprays of ammonia liquor, or ,tar and ammonia liquor. These processes are limited in their application and are relatively inflexible as to the products which may be produced in their operation.

Accordingly it is an object of the present invention to overcome the disadvantages of these known processes and to provide a process for the distillation oftar that is eiiicient in its operation, that produces commercially useful products, and that does not require excessive alteration of the present type of by-product recovery equipment.'

,In accordance with my invention tar is brought into direct Contact with coal distillation gases in such a manner that the gases are substantially enriched in tar constituents; the gases are employed at a temperature above that at which decomposition of pitch constituents takes place but the distillation is controlled in such a manner as to prevent any substantial decomposition and coking of -the pitch products produced.

More particularly, by my process a major portion of the coal distillation gases of a plant are treated in the customary manner to recover coal tar. A portion o f the ovens or retorts of the plant, however, I connect to a tar still so that the gases drawn off from the ovens may be introduced while yet at a temperature above that at which rapid decomposition of pitch constituents takes place say-above 350 C. into the tar still.

When coke oven gases are brought into contact with a stream or body of tar in the collecting main as in prior processes, the collecting main tends to become pitched with the resultant formation'of coke-like deposits and clogging of the main. I have found that by continuously flushing the still surfaces brought into contact with the high temperature gases, this pitch and coke `formation-on the surfaces and consequent clogging of the still with pitch and coke accumulations may be substantially completely avoided yet the quantity of tar or pitch introduced may be regulated-so that the temperature thereof will be raised to a point where practical distillation is effected by the hot gases, for example, to above 125 C. and even up to-300 or 350 C. Unless the tar is preheated above 40 C., the temperature at which tar ordinarily is conveyed through pipe lines, the amount of tar introduced into the hot gases should be limited to twenty gallons orless per 1000 cubic feet (calculated to standard conditions 60 F., 30 inch mercury pressure) of the hot gases at say 550 C., in order to obtain distillation to a practical degree. Where the tar is introduced at a higher temperature or where gases at higher temperature are employed, the amount of tar may be increased above this amount. v

In order to obtain distillate oils apart from the tar recovered from the gases of the coal distillation plant, the gases employed for the tar distillation according to my process, are cooled apart from the remainder of the gases from the plant to recover these oils.

In carrying out my process in coke oven plants I preferably employ only a minor portion of the'total number of ovens' at the plant, collecting the gases from say 1 to 6 or 8 of the ovens of a 60oven battery, and .employing the gases of these ovens for the distillation of tar from the remaining ovens. I prefer to insulate the main or mains from the ovens to the tar still as well as the tar still. itself in order to obtain the maximum heating effect from the gases em- -ployed for the tar distillation, to prevent condensation of pitch constituents on the walls of the main, and also to avoid undesired changes in the system as a result of varying weather conditions. By introducing the coal distillation gasesinto the tar still at a temperature not greatly below that at which they `leave the ovens,

say at 400 to 600 C. a greater degree of enrichl ment may be obtained than can be obtained using the gases at lower temperatures and a small-- ler volume of gases need be treated for the recovery of condensable oils distilled from the tar. However, it may be desirable to regulate the temperature of the gases before introducing them` into the tar still. For this purpose the gases may first be sprayed or otherwise intimately contacted with a cooling fluid such as ammonia liquor to partly cool them. By proper control of the cooling spray accurate temperature regulationand a Y uniform distillation `effectmay be obtained.

In the normal operation of a coke oven battery the gases given off from'each individual oven are, immediately after the chargingv of that oven, relatively rich in volatile oils, and contain relative- 1y small quantities of free carbon. As the age of the coking charge increases, the gases given off from the oven contain a lower ratio of volatile oils to free carbon. Immediately after the charging of the oven, gases and vapors are,

tion, composition and temperature wo-uld vary depending on the age of the coking charge, and

,for this reason some method of regulation, such as indicated above, would be desirable.

various temperatures.

I have found, however, that by collecting and mingling gases from a plurality of ovens at different ages of Athe coking charge gases of relatively uniform temperature and composition may be obtained so that any additional regulation may be obviated. Accordingly, in th'e preferred embodiment of my invention I 4collect gases from 2 up to 8 or more adjacent ovens of a coke oven plant in a single insulated header and convey them to the tar still. ASince in the ordinary operation of charging coke ovens adjacent oven vcharges are at widely varied ages, I obtain a mixture of gases the composition and temperature of which does not vary so as to'substa'ntially affect the tar distillation over an extended period of time.

Usually it is desirable that the ovens connected to the tar still be provided also with connections to the collecting main of the usual by-product recovery system so that if it is desired to reduce the quantity of the gases employed in the distillation of tar, for instance as when low melting point pitch products are produced Ior small volumes of tar are to be distilled and there is thus a surplus of gas from the ovens connected to the still, a portion of these ovens may be disconnected from the still and connected with the usual by-product recovery system. In this way large variations in demand on the tar distillation capacity of the unit may readily be obtained.

In order to obtain the benets of my distillation process, the gases should be brought into suiciently intimate contact with the tar so that the oil vapor content of the gases after the tar distillation is two or more times that of the usual fresh hot coke oven gases, and I prefer that the gases should be enriched to six or eight or more times their normal oil'vapor content. i

The tar to be distilled may be raw coal tar containing the usual small percentage of Water. However, because of the high sensible and latent heat of water as compared with coal tar oils and because of the low boiling point of water, the distilling capacity of a denite amount of the hot gases can be greatly increased by preheating the tar to vaporize water from it, for example, to a temperature around or 150 C., and the distillation capacity can be still further materially increased by preheating the tar to a higher temperature in order to supply from low temperature sources as much as possible of the latent and sensible heat required for distilling from the tar the oils of low and medium boiling points. For example, an increase in preheating oi the tar from 100 to 200 C. before admitting it into the still resulted in an increased capacity of distillation for unit quantity of hot gas of about 40% to produce pitch of the same melting point l(around 400 FJ, and the distillation capacity of the gas per thousand cubic feet was increased from about 7.8 gallons of tar to about 10.8 gallons of tar. The following examples indicate the distillation capacity of a hot gas with tar added at The tar when preheated to higher temperatures was preheated indirectly by the-hot enriched gas leaving the tar still. The

hot `gas in each case entered at about 650 C. and.

It will Abe understood by those skilled in the art that by utilizing the enriched coal distillation gases at a low temperature (or by using a secondary heat source) to supply sensible and latent heat for the distillation of low boiling tar constituents, the hightemperature of the hottest gases may be conserved to supply latent and sensible heat for the distillation of high boiling tar constituents whereby high melting point pitch may be produced. Y

The preheating of the tar, before introducing it into the still, advantageously can be accomplished by heat interchangewith the hot gases and vapors after they leave the still. A very considerable preheating of the tar can be accomplished in this way at the same time that the gases and vapors are themselves cooled and `part of the heavier oil constituents condensed therefrom. Other sources of heat may of course be utilized if desired either alone or in addition to the heat from the distillation gases for preheating the tar.

A particularly advantageous method of supplying the tanis to preheat it and then bring it into direct contact with the hot gases and vapors leaving the still. Accordingly, by bringing the tar in a preheated condition into intimate contact with the escaping gases and vapors, the tar of oil vapors in the gases increased Without excessively cooling the gases or condensing and removing from them any vsubstantial amount of the oil vapor constituents carried thereby. The thus preheated and partially distilled tar can then be supplied to the still.

By operating in the above manner, the distillation capacity of the still can be greatly increased so that the total enrichment of the gases can be carried to a high degree. It will be evident, therefore, that my invention comprehends a preheating or partial distillation step;v hence the term tar as used herein is intended to cover not only raw tar or dehydrated tar but tar Yfrom which a substantial portion of oils have been removed as well. Such products are frequently called pitch and are also to be' included by the term pitch herein where such meaning is not otherwise inconsistent with the disclosure. y

It is important that a moving lm of liquid be maintained on surfaces' of the tar still that otherwise would be exposed to contact with the hot coal distillation gases above a temperature that would rapidly evaporate the oils in the tar or pitch and even decompose the hydrocarbons,

distillation be supplied to the surfaces in such j'.

volume and in such va manner as to *keep them covered with a quickly moving film of tar or pitch that flushes any solid matter from the walls of lthe still and eiectively prevents accumulation of pitch and consequent formation'of coke on these can be partially distilled andthe concentration 115 walls. For this purpose suitable means should be provided for continually supplying pitch or tar to the interior surfaces of the still. The walls of the still should preferably be insulated to avoid loss of heat to the atmosphere. The inner surfaces exposed to high temperatures shouldbe flushed; the flushing liquid may be tar to be distilled, partially distilled tar, or pitch. In many cases the composition of the flushing liquid may vary throughout the still depending upon the temperature of the gases in the particular zone being flushed. N

After the gases have been partly cooled by the distillation of the tar or pitch in the still, their tendency to dry out or decompose pitch on the walls of the still, of course, is less than that of the original hot gases. Consequently it may be in many cases that thorough flushing of the still walls is not essential in those portions of the still near the outlet for the coke oven gases.

In general coke oven gases at a temperature above 350 C. tend to rapidly decompose pitch accumulations with which they come in contact and hence where the walls of the still otherwise would be exposed to gases above this temperature a film of the flushing liquid moving at a sufficiently rapid rate so as to'carry away solid particles should be maintained thereon. This may be effected by spraying the tar or pitch against the walls of the still or by otherwise creating the lm thereon. The 'rate of decomposition increases rapidly with increase in temperature above this value and at 400 C. is such that appreciable decomposition may be effected in only a few seconds where high melting point pitches are being produced. Consequently it is desirable that the gases be rapidly cooled below this temperature; for instance, it is preferable that the temperature of the gases be above 400 C. not more than about two seconds after their entry into direct contactwith the tar or pitch in the still.

When operating at these high temperatures the pitch flushing the walls of the tar still may actually be undergoing decomposition, but since it is moving and continually being replaced by more of the flushing liquid, it is removed while still fluid and before decomposition is complete, thereby preventing the accumulation of undesirable deposits.

The tar to be distilled may be contacted with the coaldistillation gases-by spraying the tar into the gases or by bringing it into contact with the gases in the form of a sheet or film or by otherwise providing intimate contact between the tar and the gases. The tar and gases may travel through the still iny a generally concurrent or countercurrent direction.

Various mechanical devices may be employed to accomplish these objects. For` example, a body of tar and pitch undergoing distillation may be maintained at the bottom of the tar still and hot coal distillation gases may be introduced into the still and passedtherethrough above the body of tar. Suitable meansthen may be provided for bringing tar from the body thereof into intimate contact with the gases passing throughthe vapor space vof the still thereabove and for thoroughly flushing the exposed walls of the still with the tar or pitch being distilled. For this purpose suitable agitating devices may be employed, such as a horizontal spray roll or a plurality of rolls or elongated cylinders, rotating rapidly, and with the cylindrical surface dipping into the tar or pitch at the bottom of the still.

The agitator may be disposed and rotated in such a manner as to throw a sheet or-film of tar or pitch over the surfaces of the still, forming for example a rapidly moving conduit of liquid through which the hot coke oven gases pass. Or the spray roll may be disposed and regulated so as tosubstantially completely ll the interior of the still with an exceedingly fine intense spray of tar and pitch that is projected against the walls of .the still and thereby flushes these surfaces. Such a roll may be a cylindrical roll with smooth surfaces or it may have circumferential grooves or ribs or disc-like projections.

The invention, however, in its broad aspects is not limited to any particular mechanical contacting device but comprises any suitable method that will insure` direct contact of the tar with the such a device effective contact of the tar with the gases and thorough flushing of the still walls may be obtainedI and the tar may be distilled advantageously to produce pitch products of high melting point and unusually high percentages of oil `distillate from the tar. It will be understood that the pitch is repeatedly thrown up into the gases and over exposed still surfaces so that inv its progress through the still anyparticular unit of pitch may be thrown into the gases a great many times. In this way a high degree of intimacy of contact between tar and pitch and a regular and controlled increase of temperature of the pitch is accomplished.

The volume of intimacy of contact also should be regulated when gases are employed at a temperature above 400 C. so that the gases are cooled below this temperature promptly after their entry into the tar still.

By imposing these conditions a minimum decomposition of the tar in the distillation is obtainable. f'

The gases employed for the tar distillation may enter the tar still at one or at a number. of points. In general, however, in the production of high melting point pitches, especially, it-is desirable that the gases in contact with the pitch product of high melting point should be at a relatively low temperature and consequently in such operations the gases'preferably should enter the still at a point remote from the pitch outlet. In producing pitches of 350 F. melting point or higher especial care must be taken since there is considerbalance should be maintained between the quantity of gas employed for the distillation, `the quantity of tar being distilled` and the intimacy of Contact of tar or pitch and the gases. In the production of such products as 400" F. melting point pitch it is particularly desirable to avoid excessive heating of the pitch. especially that of above 200 or 250 F. melting point. since this pitch, already freed of the major portion of volatile constituents will. as aforesaid, be rapidly coked. With the production of lower melting 'i point pitches this diiculty diminishes and where pitch of melting point of 90 F. or 150 or even 200 F. is being produced less care is necessary.

The process is applicable to the production of pitchesA of various melting points and distillate oils of various properties. Pitches of melting points from 110 F. or lower up to 400 or 450 F. or higher may be prepared. The amount of distillate, of course, will be greater and will contain more high boiling constituents where pitches of high melting point are produced. Also the gases to retain this distillate must be maintained at a higher temperature. Under these conditions the distillation capacity of the gases is reduced. 'Ihis may in part be compensated for, however, by employing the gases to preheat tar in indirect contact therewith. The following table illustrates the eiect, upon the distillation, of producing pitches of high or low melting point from raw coke-over tar (containing 2% of water) originally at a temperature of C.

The results obtainable are given for coal distillation gases (containing originally 0.7 gallon of tar per 1000 cu. ft.) at 350 C. and 650 C.

" In column:

I. Pitch melting point y II. Oil distilled off by the hot gases, expressed as per cent of tar III. Total oil content of resultant' gases (a) With gases originally at 350 C.

(l) Expressed in multiples of original total tar content (2) Expressed in multiples of f A original oils of corresponding boiling range (b) With gases originally at 650 C.

(1) Expressed in multiples of original total tar content1 (2) Expressed in multiples of original oils of corresponding boiling range IV. Final gas temperature (a) With 'gases originally at 350 C. (b) With gases originally at 650 C.

1 1i (a) (b) (a) (o (1) (2) (l) (2) 1"'. Percent A C. C'. 11o 2o 2.2 11 4.4 22 13o 145 45 2.9 6.4 5.7 14.6 185 ,200 2.9 A5.5 5.8 12.7 .205 22o 3.1 4.7 7.2 `11.1 225 245 2.9 4.2 7.5 10.3 23ov y 255 'I'hese gures should be taken as illustrative only as variations in the temperature, water content, and specific heat of the tar, and the oil content of the pitches produced will correspondingly change the distillation capacity of the gases. As indicated, using tar at 50 C. the gases may be enriched to from 2 to 3 times their original" .oil vapor content when the gases are initially at 350 C., and more than seven times their original oil vapor content when the gases are initially at 650 C. The percentage enrichment may be increased further to more than double these values by initially supplying the tar in a preheated condition.

'I'he total distillate produced by the present process, which may represent as much as 75% or more of the tar distilled, can be condensed'as a single composite oil and employed, for example as creosote oil; or the admixed gases and vapors can be fractionally cooled and fractionally condensed and a plurality of oil fraction recovered. A sample of oil produced showed a specific gravity at 38 C. of l1.110,'only a tracel of free carbon and, when subjected to distillation in accordance with the American Society of Testing Materials method `showed up to 200 1.1%, up to 210 2.3%, up to 235 8.3%, up to 270 22,4%, up to 315 34.3%, up to 355 48.8%, distilled off. y

It will be evident that the distillation 'can be carried out without the production of the maximum oil yield and the highest melting point pitch, and that under such conditions the process is well adapted for distilling an increased amount of tar for the production of a pitch of lower melting point and a correspondingly lower oil yield; but the distillation can nevertheless be carried out with the production of an unusually high oil yield corresponding to the melting point of the pitch produced. When distilling coke-oven tar, for example, in simple externally heated stills of 10,000 gallons capacity, the `oil yield is only around 44% when the distillation is carried to the point of producing pitch of around 300 F. and coking may begin before pitch of 400 F. melting point is reached. With other methods of distillation somewhat higher yields of oils can be obtained on distillation of tar to 300 C.' melting point pitch. The production of pitch of as high as 400 F. melting point, however, has heretofore involved techincal difficulty, and resulted in relatively low oil yields; by the present process production of pitch of this melting point is greatly facilitated and yields of around '75% or more of distillate oil can be obtained from coke-oven tar when distilled to the point of producing pitch of melting point around 400 F. or higher; while with the production of pitch of lower melting point, around 300 F. melting point, it is possible to produce oil yields representing around twothirds or more of the tar distilled. It will be understood, of course, that different tars vary in their oil content, depending upon the coal subjected to coking, and the nature of the coking operation so that the percentage of oil obtainable from coke oven tar from one plant may not represent that obtainable from tar from another plant operating with diiTerent types of ovens upon different coals and with a diierent coking period or with ovens of varying dimensions and heating characteristics.

The invention will be further described in connection with the accompanying drawings which illustrate several methods for carrying out the improved process of the invention.k The illustration is of somewhat conventional and diagrammatic character.

In the drawings:

Fig. 1 is a plan, with parts broken away, of part of a coke-oven plant showing part of the ordinary by-product recovery system and also showing more particularly the tar distillation apparatus for effecting the process of the present invention;

Fig. 2- is a vertical sectional view through the header andstill, part being shown in elevation;

Fig. 3 is a section taken on the line 3-3 of Fig. 2:

Fig. 4 is a transverse section taken. on line 4 4 of Fig. 2:

Fig. 5 is a sectional view showing 'an alternative type of tar still that maybe used for carryying out my invention;

Fig. 6 is a section on line 6-6 of Fig. 5;

Fig. 7 is a sectional view showing an alternative type of tar still that may be used for carrying out my invention;

Fig. 8 is a section on line 8 8 of Fig. 7;

Fig. 9 is a vertical sectional view showing a somewhat diierent arrangement of tar distillation apparatus;

Fig. 10 is a plan view of the apparatus of Fig. 9.

With especial reference to Figs. 1 and 2 of the drawings the numeral 1 indicates a coke-oven battery Vhaving coke ovens 2 arranged inthe conventional manner and suitably heated by heating lues (not shown) therebetween. The individual ovens are provided with uptake pipes 3 connecting the ovens with a collector main 4 having a pitch box 5. The collector main is connected by means of cross-over main 6 to primary cooler '7. This cooler is then connected by the gas conduit8 to an exhauster 9. Draw-offs 10 and 11 are provided to convey tar and cooling liquor 'from pitch box 5 and primary cooler 7 to the decanter 12 where the aqueous liquor may be separated from the tar. A suitable tank 13 may be provided for` collection of tar from the decanter 12. This apparatus is but a conventional coal distillation and by-product recovery system well known in the art and has been shown and explained merely to more clearly show the relation of the applicants process to the ordinary recovery system.

A portion of the coke ovens 2 of the battery, for example 4 to 8 more or less of the ovens, are connected by additional uptake pipes 14 to a header 15. The header 15 is joined to one end of an elongated distillation chamber 16. This distillation chamber has near the same end thereof a tar or pitch inlet 1'7 and has at the far end an outlet conduit 18 entering a tower 19 at the bottom thereof.

The uptake pipes 14, header 15, distillation chamber 16, conduit 18, and tower 19 are provided with heavy heat insulation 14', 15', 16',

etc. in order to prevent loss of heat through the walls of these elements of the apparatus. This insulation may be of any suitable type and for those portions of the apparatus subjected to high temperature, for example the uptake pipe, header, and distillation chamber, should be adapted to withstand temperatures in the neighborhood of that of the coke oven, say 600 C. or more.

Distillation chamber 16 has disposed at one side and near the bottom thereof a spray roll 20. This spray roll is preferably substantially cylindrical in cross-section and may be of uniform diameter throughout its length or may be of varying diameter so as to present a ribbed surface. The spray roll illustrated isa smooth cylinder about 10 inches in diameter. It advantageously may be from one foot to iive feet in length and may be -up to ten feet or more in length depending upon the capacity desired and products to be obtained, etc. For maximum eiciency of operation and minimuml power requirements the surface should be relatively smooth circumferentially of the cylinder. This is not essential, however, and a rough irregular, or corrugated surface is satisfactory.l A motor 21 is provided for rotating the spray ro1l20. The spray roll 20 and motor 21 should be offa construction adapted for rotation vat high speed for instance 90o to 1200 a. P. M. At. the ena of the distillation chamber 16 remote' from that at which the hot gasfheader is joined thereto, there is p'rovided a pitchbox 22 having a draw off 23. The

`moving condensate.

natalizia1 draw olf 23 is adjustable so that the level of pitch within the still 16 may be regulated by raising or lowering this arm. The arm 23 is located above a trough 24 that is provided with a water inlet pipe 25 to supply a stream of water for cooling and granulating the pitch. A bin 26 may be provided for collecting the pitch and separating it from the cooling water.

The tower 19 has the inlet thereto, from pipe 18, shielded as shown to prevent liquid in the tower from passing into pipe 18. At the bottom the tower 19 is provided with liquid draw-offs 2'7 and 28, the liquid draw-oil 27 leading to inlet 17 ofthe distillation chamber 16, and liquid draw-off 28 leading to a collecting tank 29. The tower 19 is vprovided with packing, such as checkerbrick, Raschig rings, subway grating, etc. This packing preferably is disposed in two layers 30 and 3l having a tar inlet spray 32 located therebetween for a purpose to be hereinafter more.

fully described. The tower 19 at the top thereof has an outlet conduit 33 for the passage of gases and vapors to a condenser 34.

Within the passage 33 there is provided a butterfly valve 35 controlled in conventional manner for the regulation of pressure in the tower 19 and consequently the pressure in the ovens connected to the tar distillation apparatus.

Within the condenser 34 there is provided a pipe coil I36 through which a cooling liquid may be passed in a downward direction. Pipe 33 is united to the condenser 34 at the bottom of the latter so that gases may pass up through the condenser. A suitable draw-off 37 for condensate also is located at the bottom of the condenser. From the top of the condenser 34 a conduit 38 leads to the top of a fractional condenser 39 comprising a series of cooling sections each provided with a cooling coil 40 and a draw-off 41 for re- This condenser is connected by conduit 42 to the gas conduit 8 of the main byproduct recovery system of the coal distillationplant.

Fig. 3 of the drawings is a sectional view of the tar distillation chamber 16 and shows the relation of the rotating spray roll 20 thereto. As indicated, the spray roll preferably is located at one side of the chamber 16 spaced therefrom and employed, and accordingly this has not been illustrated. A clean-out door 43 is shown for providing access to the uptake pipe and valves to remove carbonaceous material, etc., that may vcollect thereon.

In carrying out the, process of `myinvention .the apparatus above described may be operated as follows:

The ovens 2 of the battery 1 arecharged with bituminous coking coal in the usual manner, the charging being arranged so that adjacent ovens are maintained at relatively different stages of the coking cycle. It is preferable to have the order andtime of charging of the ovens 2 and the location of header 15 such that gases from ovens at widely different stages of the coking cycle enter the header so as to form `a resultant mixture the composition and temperature of which are comparatively uniform with respect to time. The hot fresh coal `distillation gases at a temperature of 550 to 850 C. are withdrawn from a major portion of the ovens of the battery through uptake pipes 3 and into collector main 4 where they are sharply cooled by ammonia liquor sprays orl other cooling means in well known manner to remove tar constituents from the gases.

In the usual coke oven operation the gases will be cooled in the collector main to a temperature of around 120 C. and heavy tar and ammonia liquor will be withdrawn through the draw-off 10 from the collector main. The gases then pass through cross-over main 6 and because of the cooling effect of air surrounding the main and of further evaporation of water into the gas will be further cooled to 75 to 85 C. At this temperature the gases enter the'primary cooler 7 where they may be cooled further by direct contact with a cooling liquid or by indirect heat exchange relation with a cooling uid to lower-their temperature to around C. 'I'he cooling of the gases in the crossover main and the primary cooler result in the condensation vof additional constituents from" the coal distillation gases and these are withdrawn through draw-off 11 as a vmixture of light tar (0r tarry oil) and ammonia liquor. The heavy tar and ammonia liquor drawn off. at 10 and light tar and ammonia liquor drawn off at 11 are collected in decanter 12 where ammonia liquor is separated therefrom. The resultant raw tar is collected in the tar tank 13.

From the tar tank 13 the raw tar may be pumped or otherwise suitably conveyed, for example, by means of pump 44 and pipe 45 to the pipe coil 36 of the condenser 34 down through which it passes ina direction countercurrent to the hot coal distillation gases passing up therethrough, whereby the tar is heated to, forr example, 80 to 200 C.

The preheated tar is passed from coil 36 to the tar spray 32 in tower 19 wherein it is sprayed onto the packing 3l withinthis tower. Additional tar also may be supplied at 46 from the same or a,

diilerent sourcewhere it is desired to run the preheater and condenser 34 at a high temperature without correspondingly increasing the ingoing tar temperature. The contact of the hot tar with the hot coke oven gases and the reduction in pressure on the tar due to its release from the spray head result in the separation therefrom of lowerboiling oils as well as water contained in the tar. The contact of the tar with the gases results in further distillation of the tarl and also in the removal from the gases of entrained constituents. As much as 5%-i to 30% of the tar may be evaporated, or distilled olf from the tar in tower 19 and the temperature of the residue may be as high as 100 to 250 C.

A portion of the partly distilled tar may be withdrawn through draw-oil? 28 and employed either as such for various commercial purposes :s: may be blendecLwith other products for the production of special, tar products.

The preheated and partly distilled tar is then at least in part withdrawn y.from the tower through outlet 27 and without great reduction in temperature is introduced into the distillation chamber 16. Additional raw tar may be introduced directlyh from pipe Jto inlet 17 of the still where desired.

Hot coal distillation gases collected from a.

minor portionv of thel coke ovens are withdrawn through the insulated uptake pipes 14 and collected in header 15 where they mingle to form a relatively uniform gas mixture. This gas mixchanber y16 at the same end thereof as the tar from the tower 19. The gas mixture' entering chamberfl may be at a temprature of 350-850 C. preferably around 600-650 C. for nthe production of pitch of 400 F. rneltingpoint.` With lower melting point pitches the higher gas temperatures become more advantageous.

Within the distillation` chamber 16, a body of. tar and v pitch undergoing 'distillation is maintained in contact with the spray roll 20 and passes through the still concurrently with the hot gases, This roll is rotated rapidly so asto bring the tar or pitch into repeated intimate contact with the hot gases in the chamber. The operation of the system may be varied to a large extent by controlling the depth of pitch in the distillation chamber. Thus, if the depth of tar or pitch is maintained such that it just contacts with the surface of the rotating ,spra'y roll 20, ne intense spray of the liquid is' thrown into the gases. This ne spray substantially fills the interior of the chamber and strikes' against the surfaces or walls therefaces andfa very intimate contact of the liquid with the gases. On the other hand, if the depth of tar and pitch in the distillation chamber is increased so that the spray roll is immersed, for

` of resulting in a continuous flushing of these ,sur-

-instance to 1/3 of its diameter in the body of;

liquid, little spray will be thrown into the gases. With the spray rollV rotating in a counterclockwise direction as' viewed in Fig. 3, however, a sheet .of tar or pitch will be carried between the rotating roll and the wall of the still at a rapid rate such that the entire surface of the still will be covered with a rapidly changing film or sheet' of the tar or pitch. With the rotating roll operated in this manner, the' distillation of the tar or pitch will be effected while the tar or pitch is contacted with the hot gases largely as a sheet rather than asa spray.

By varying the operation of the rotating roll between these two limits, the one where an ex\ i to produce an exceedingly fine spray or substantially no spray, the rotating roll is arranged to provide continuous and voluminous flushing of the surfaces or walls of the still with the tar or pitch being distilled so that during the distillation accumulation ofsolid pitch particles on these surfaces is substantially avoided. `Spray prevented from entering `the hot gas header 15 ifi any considerable amount by an extending vlip 47 so arranged as' to divide the stream of iushing liquid and to bar the passage of spray.

By introducing the tar tofbe distilled into the end of the still into which the hot gases are introduced, the pitch colder end of the still, which may be at a temperature ofonly 150to 400 C. The 'temperature at this end of thestill, of course, may be near aybe withdrawn at the` .would otherwise be the case.

produced but ordinarily should be higher when high melting point pitches are produced. Since the entering tar or pitch contains a larger proportion of volatile constituents than the pitch produced, and the distillation therefrom of such constituents causes a rapidlowering of the gas temperature and retards the overheating of the liquid, the less stable constituents are not as readily coked by the high temperature gases as Furthermore, as the gases pass through the still not only is their temperature lowered, but at the same time their oil content is raised so that they reach a condition of substantial equilibrium withlthe outgoing pitch so that the gases at the exit end of the still have little or no tendency to further distill the pitch.

Operating under these conditions| pitch of high melting point, for vexample as high as 400 F. melting point pitch or above, may be produced with an exceedingly low degree of decomposition, and especially high yields of distillate oil may be obtained, for instance 50.to '70 or 80% of the tar may be recovered as distillate.` The gases enriched in oil constituents by the distillation of tar from the distillation chamber 16 may leave this chamber while yet at a high temperature, say 150 to 350 C. or above, depending upon their temperature at entry, and upon the regulation of the distillation.

When the tar or pitch distillation is controlled so as to maintain a fine spray of tar or pitch in the distillation chamber, the gases may be cooled almost instantlyfrom their maximum temperature to below 400 C. and this is desirable in any event where decomposition of pitch constituents is to be avoided; free carbon constituents will be removed to a considerable extent from the gases and the gases entering tower 19 will contain relativelysmall amounts of such constituents, but may contain ysubstantial quantities of entrained spray from the distillation chamber. Satisfactory vscrubbing and distillation have been obtained in stills having a spray roll, as abovedescribed, in which the gases were cooled from an inlet temperature of about 600 to 650 C. to a temperature of around 400 C. in 2 seconds or less. 'Ihe packing 31 is covered with a film of ingoing tar or partly distilled tar and thegas passing up through this wet packing is brought into intimate contact with an extensive surface of the tar so that entrained spray particles are effectively removed. The packing 30 serves further to remove any remaining entrained material and prevents substantial amounts of tarfrom. the 'sprayhead -32 from passing out to the condenser. The diameter of tower 19 'is great enough to reduce the`velocity of the gases to the point below which entrained spray will not be carried past the wet packing in undesirable amount. For plants operating with six ovens or fewer, 30 inches has been found a satisfactory diameter.

Consequently when the tar or pitch distillation is effected in this manner, the gases leaving the tower- 19 through conduit 33 will contain a relatively small amount of free carbon or pitch particles and consequently will, upon subsequent condensation, yield relatively clean oils.` Thus a condensate fraction may be directly obtained conforming to specifications for commercial creosote oil, which specications require an oil to contain not more than .5% free carbon; i. eI',

`material insoluble in benzol, or for a commercial carbolic oil, containing 0.2% or less of free carbon. The degree of cleaning of the gases will, of

course,depend upon the extent of contact of gases with tar spray and consequently where less spraying of the gases is effected less cleaning will result. The recovery of clean oils on the other hand depends not only on the cleaning of the gases, but also on the degree of enrichment of the gases; so that-as the degree of enrichment is increased, gases having the s ame quantity of free carbon or pitch particles will produce a condensate containing anincreasing ratio of oil to free carbon or pitch particles. This illustrates the desirability of employing the coal distillation gases at their maximum temperature and also preheating the tar to asr high a temperature as feasible, for only by this means can the maximum enrichment of the gases be secured. Oil suitableY for creosoting and containing less than .5% free carbon may be obtained readily by operating a spray roll as described above to produce a line spray of tar or pitch where the distillation is controlled so as to enrich the gases say to four or more times their original oil vapor content with respect to oils condensing out in the creosote oil range. 1

This process permits of the direct recovery of oils of very low free carbon content. The maximum removal of free carbon is obtained by a scrubbing of maximum intensity accompanied by the highest possible degree of enrichment.

When the 'recovery of oils of higher free carbon 1")5 content is allowable, either the scrubbing or the enrichment or both may be decreased.

Free carbon or tar fog, when present in the gases, is found in all condensates removed from those gases but is usually found in greater quantities in the higher boiling condensates than in the lower boiling condensates. By taking advantage of this, condensate fractions very low in free carbon may be obtained. For example, when it is desired to recover a carbolic oil of suiiciently low 1.1.5

free carbon content to permit extraction with caustic without danger of emulsion formation, a

creosote oil fraction may first be removed from the scrubbed and enriched gases by controlled bolic oil fraction`will have a lower percentage content of free carbon than the total condensate would have contained.

-fractional condensation and a carbolic oil frac- .tion then recovered by condensation. Such car- Much larger percentages of free carbon are sometimes permissible in certain commercial tar oils than are permissible in the clean tar oils. For instance, a tarry oil containing as much as 2% of free carbon may be satisfactory for many purposes. the degree of enrichment may be much less for the preparation of such products.

In general when it is desired to produce oils containing lless than .5% of free carbon, the

The thoroughnesspf scrubbing and scrubbing will be regulated to remove at least 50% i135' of the free carbon originally contained in the coke oven gases and where a low degree of enrichment, say to twice the original vapor content, is obtained, up to around 90% or more of the free carbon should be removed. While for the "4t production of tarry oil's containing not more than 2% of free carbon with an enrichment to twice the original oil vapor content, perhaps only 60% of 4the free carbon need be removed and with greater enrichment a considerably smaller perlie centage, varying inversely with the degree of en' richment. Usually, to produce tarry oil containing not more than 2% free carbon,V the ratio of pitch to oil content of the gases should be reduced to about one-quarter or less of the normal denser 39. If desired, these products may'be ratio, by the scrubbing and distillation, after which the tarry oil may be directly condensed. This, of course, will depend in each particular instance upon the original content. of free carbon and oil in the gases used for the distillation.

The hot enriched gases pass upwardly through condenser 84 in indirect heatl exchange relation with tar passing downwardly therethrough and are cooled by this tar so as to condense high boiling constituents. Where high melting point pitches are produced, that is pitches of 200 F. melting point or above, more particularly pitches of 350 F. melting point or above, the condensate will contain high boiling greasy or resinous constituents which at ordinary temperature are of a non-uid nature. By passing thev gases upwardly through the condenser the high boiling greasy or resinous constituents are condensed in the lower portion thereof and high boiling oils are condensed in the upper portion of the condenser. 'Ihe later condensed high boiling oils pass downwardly over the pipe coil washing the surfaces thereof and dissolving therefrom the higher boiling greasy or resinous constituents condensed in the lower portion of the condenser. The temperature of the gases advantageously may be reduced in condenser 34 from the temperature at which they leave tower 19, namely 100 -to 350 C. down to 70 to 200 C.

The gases thus freed from high boiling greasy constituents and highest boiling oils then pass into condenser 39 through which they pass over cooling coils 40 through which any suitable cooling liquid may be passed, for example, cold water. The cooling of the gases in this condenser39 may be regulated so as to produce a plurality of oil fractions such as a high boiling oil, a middle oil, and a relatively light oil or more or less fractions may be condensed. It .may be desirable, for example, to collect only two products, a creosote oil, and a carbolic oil or even only one product depending on the nature of the products desired and also on the regulation of the condenser 34.

The temperature to which the gases should be cooled in order to condense these fractions willI depend in part upon. the degree of enrichment of the gases. `In general it may besaid that for the condensation of a particular commercial oil product the dew point of the gases for that oil is elevated in the neighborhood of 20 C. for each doubling in the enrichment of the gases above their normal content with'respect to oils of that character for a limited range of increase. Where the enrichment is increased to around ten times the normal oil vapor content of the gases, the dew point will be elevated about 66 C. above the -normal dew point. The condensation range of a particular oil product, however, may be affected by other constituents. Thus, where the gases are enriched in both creosote and carbolic oil constituents, the dew point of the gas for carbolic oil will be elevated as well as that of the gas for creosote, oil so that the lower limit of the creosote oil fraction condensation range will be correspondingly elevated.

above-mentioned may be recovered from the con- `type of agitator.

Figs. 5 and 6 show'a somewhat dierent type l of tar still employing a paddle type of mechanical agitator 51 instead of the spray roll 20 of Figs. 1 and 2. With this type of agitator the same or a different shape of still may be employed. As shown in Fig. 6 the still may be of generally compressed circular or elliptical cross section, the primary requisites being a free passage for the hot gases through the still, and a shape such that the spray will adequately flush all of the surfaces exposed to the hot gas.

'Ihe operation of the still illustrated in these figures is substantially the same as that of the still shown in Figs. 1 and 2. The hot gases entering from the hot gas header 15a pass length- Wise through the still and out through the conduit 18a for further treatment, .e. g. condensation of contained oils. A motor 21a is arranged to rotate the agitator 51. The hot or cold tar or semi-pitch to be distilledventers the still through the inlet 17a and the pitch product may be withdrawn at the far end of the still by means of a suitable pitch trap 22a as previously explained in connection with Figs. 1 and 2. With this paddle type of still the agitator should not be deeply immersed in the tar or pitch in the bottom of the still as this usually will result in an excessive power consumption to operate the agitator. Preferably the level of tar or pitch in the still should be controlled so that the blades 52 just touch or dip into the liquid in the bottom of the still. In Figs. 7 and 8 a similar still Iis illustrated employing rotating discs instead of a paddle The operation is essentially the same as with the spray roll or paddle spray type of still. The hot gases from the coke ovens enter the still by means of hot gas header 15b and the tar or pitch is introduced at l'b. The gases and vapors are withdrawn through the conduit 18h and the pitch product is' withdrawn through a suitable trap 22h. The agitator in this case comprises a plurality of discs 53 rotated by the motor 2lb. With this type of agitator the body of partly distilled tar or pitch in the still may immerse the discs to a considerable extent without the loss of power that would result with apparatus such as illustrated in Fig. 5. 'I'he pitch collecting on the surfaces of the discs is hurled by centrifugal force off the sides thereof producing sheets of spray coplanar with respect to the j sides of the discs so that the gases will pass through a series of these sheets of spray as the gases pass lengthwise through the still.

InFigs. 9 and 10 a somewhat different type of tar still is shown. In the` stills so far4r described the distillation has been effected by lifting a portion of a body of pitch up' into the gases re, peatedly either by spraying it into the gases so that it will again drop into the body of tar or pitch or by forcing the tar or pitch as a sheet thereof over the walls of the still in such a manner as to return the pitch to the body thereof. The apparatus illustrated in Fig. 9 may be operated so as to repeatedly bring the tar into contact with the gases or it may be operated so` as to distill the tar with only a single passage thereof through the gases,

This apparatus comprises a tower 55 having a spray head 56 at the top thereof for spraying tar or pitch down through the tower. The hot gas headerl 15e enters the tower at or near the top thereof and a gas outlet 57 is arranged V-near the bottom of the tower. A pitch draw-off boX 58 with adjustable spout 58 isv provided at the bottom of the tower.

The sprayA head 56 is designed to produce@ fine spray of tar in the tower and also to cover the walls of the tower with a sheet or film of the liquid being distilled. This sheet or lm should be such as to prevent contacting of the hot gases at their'maximum temperature with bare surfaces of the tower. Suicient tar ror pitch therefore should be permitted to ow against the walls of the still so as to provide a continuous rapidly flowing lm of the liquid on these surfaces.r The nozzle or spray head 56 may be designed sol that either the size of the spray of tar or the volume of the flushing lm of tar may be varied, if desired; hence the degree of distillation of the sprayed tar may be regulated to be the same as or greater or smaller than the degree of distillation of the film of tar on the walls of the still. A plurality of spray devices, of course, may be employed for producing the spray of tar and for securing the proper flushing effect. Y

`Spray tower 55 has connected therewith by gas conduit 57 a second tower 59 that may be provided with packing or baille plates or bubble trays, etc. so as to provide intimate contact of .the gases passing therethrough with liquid that provided near the top of this tower and a drawoif box 63 with adjustable spout 63' is provided at the bottom thereof for the removal of tar or semi-pitch.

Located at the bottom of the tower is a pump 64 driven by motor 65 for conveying tar or pitch from the bottom of `tower 59 through pipe v66 to the spray head 56. A Weir 67'is provided in passage 57 to separate the liquid in the bottom of tower 59 from that'in the bottom of tower 55.

The towers 55 and 59, pump 64, and the hot gas vand hot pitch conduits should be provided with suitable heat insulation to avoid heat loss.

In the operation of this apparatus hot gases fresh from the coal distillation battery or perhaps partly cooledby suitable means but still at a temperature not less than 350 C. are introduced into tower 55 by means of the conduit 15o. At the same time preheated and partly distilled tar is pumped from the bottom of tower 59 through conduit 66 to the`spray-head 56. The gases pass down through the tower concurrently and in intimate contact with the spray of tar from spray head 56 whereby volatile oils are vaporized from the tar and the gases are partly cooled. The cooled gases are withdrawn at 57 and pass up through tower 59 and out aty 62 after which they may be brought into` indirect contact with ingoing tar to'preheat it. The preheated tar, or tar not so preheated, is introduced at 61 to the spray head 60 and passes down through tower 59 countercurrently and in intimate contact with the gases passing u p therespray head 56 and is thus spr'ayed into the gases, v

a sumcientaportion being directed against the walls of the tower 55 to keep. these walls free from static pitch accumulations. r

' yIn some cases it may be preferred to effect the distillation without any substantial quantityof spray in the tower 55 and to effect the entire distillation of the tar or pitch while it is maintained as a. -moving lm on the walls of the tower. When operated in this manner the still, of course, will not have the distillation capacity that it would if operated so that the tar is in part distilled as a spray..

The pitch resulting from the distillation is collected at the bottom of the tower 55 and may be withdrawn at 58. If it is'desired to recirculate a part of the pitch, thus increasing the Volume of flushing liquid available, this recirculation may be effected by permitting the level of pitch in the bottom of the tower to rise above the weir67 by adjusting the height of the spout 58' so that it flows over into the chamber of tower 59with which pump 64 is connected-and will be carried in admixture with the partially distilled tar from the tower 59 up to spray head 56. It may be desirable in-some cases even to provide separate recirculation means for the pitch in which case all of it may be supplied to the walls as flushing medium or all may be sprayed into the gases. .Suitable agitating means may be provided, if desired, to maintain the body of pitch at the bottom of the tower in a uniform condition. However, in ordinary operations the gases leaving this tower will'be at a suiciently low temperature, say below 400 or 300 C., so that decomposition of the tar in the body thereof will be negligible. Also by the time the gases reach the bottom of the tower they ordinarily will be in substantial equilibrium with the pitch or tar; hence little distillation will take place at this point. When the tar introduced at inlet 61 is preheated, this inlet also may be insulated. The gases leaving thestill through conduit 62 may be passed to' suitable condensing apparatus, such as described in connection with Figs. 1 and -2 of the drawings. In the operation of this apparatus' the spraying of tar in tower 55 should be conducted so that the gases will be cooled below a temperatureat .which .rapid decomposition of pitch occurs before these gases leave the still; that is, before lthey pass outthrough the outlet 57. In this manner coking of the pitch in the bottom of the tower is minimized and the gases do not tend to form pitch and coke accumulations in the packing of the tower 59. Tower 59 serves not only to partly distill the ingoing tar but also serves to remove entrained spray particles and entrained free carbon partifloat tests of 50-100 seconds at 32 C. When the former type of products is produced the distillate obtained will contain the volatile tar constituents up to and including high-boiling resinous or greasy constituents. When the latter type of products is produced the distillate may be only carholic oil, the heavier oils being collected as a part of the tar or pitch residue. Hence it will be evident that my process is capable of wide application with the production of tar distillation products of greatly varying composition.

rf'his application is in part a continuation of my prior applications Serial No. y326,760 and 326,770, filed December 18, 1928, 329,197, led December 29, 1928; and 369,193, led June 7, i929. Y

claim: l. The method of distilling a material of the group consisting of tar, tarry oil, and pitch, which comprises introducing hot fresh coal distillation gases while yet at a temperature above 350 C. into a still, introducing the material into the still into direct contact with'the fhot gases therein, regulating the volume of the material and the contact of the material with the gases so that the material is heated to at least 125 Ci and is distilled and the gases are only partly cooled and are enriched to at least twice their origmal oil vapor content, and simultaneously flushing the entire surfaces in the still exposed to the gases at said high temperature so as to maintain thereon a continuously moving liquid film.

2. In the operation of the by-productrecovery system of a coal distillation plant the process which comprises collecting a part of the hot fresh coal distillation gases from the plant and cooling them to separate tar containing pitch constituents, separately collecting another part of the hot fresh coal distillation gases and introducing them while yet at a temperature above 350 C. into a still, introducing a material of the group consisting of tar, tarry oil, and pitch containing the aforesaid pitch constituents into the still into direct contact with the hot gases therein, regulating the volume of the material and the contact of the material with the gases so that the material is heated to at least 125 C. and is distilled and the gases are only partly cooled and are enriched to at least twice their original oil vapor content, simultaneously flushing the entire sur-` faces in the still exposed to the gases at said high temperature so as to maintain thereon a continuouslyv moving liquid film, withdrawing the hot enriched gases from the still, and cooling them apart from the aforesaid Yone part ofthe gases to recover condensable oils therefrom f 3. The method of distilling a material of the group consisting of tar, tarry oil, and pitch, which comprises introducing hot fresh coal distillation gases while yet at a temperature above 350 C.

vinto a still, introducing the material into the still into direct contactV with the hot gases therein, and passing the material through the still in a generally cocurrent .direction with the gases passing therethrough, regulating the volume of the material and the contact of the material withv above the melting point of the material contacting therewith.

4. In the operation of the by-product recovery system of a coal distillation plant the process which comprises collecting a part of the hot fresh coal distillation gases from the plant and cooling them to separate tar containing pitch constituents, separately collecting another part of the hot fresh coal distillation gases and introducing them while yet at a temperature above 350 C. into a still, introducing a/ material of the group consisting of tar, tarry oil, and pitchv containing the aforesaid pitch constituents into the still into direct contact with the hot gases therein, and passing the material through the still in a generally cocurrent direction with the gases passing therethrough, regulating the volume of the material and the contact of the material with the gases so that the material is heated to at least 125 C. and is distilled and the gases are only partly cooled and are enriched to at least twice their original oil vapor content and the gases and material are brought nearly to-equilibrium, simultaneously flushing the entire surfaces in, the still exposed to the gases at said high temperature so as to maintain'thereon a continuously moving liquid film, withdrawing the hot enriched gases from the still and cooling them apart from the aforesaid one part of the gases to recover condensable oils therefrom.

5. The method of distilling tar to produce pitch and distillate oil, which comprises distilling olf from the tar a portion of the volatile oils contained therein so as to form a hot pitch residue containing volatile oils, introducing hot fresh coal distillation gases while yet at a temperature above los 350 C. into a still, introducing thehot pitch' residue into the still into direct Contact with the hot gases therein, regulatingthe volume and contact of thev pitch with the gases so that the pitch is heated to at least 125 C. and volatile oils are distilled from the pitch and the hot gases are partly cooled and enriched to at least twice their original oil vapor content, simultaneously flushing the entire surfaces inthe still exposed to the gases at said high temperature so as to maintain thereon a continuously moving film of the pitch being distilled, withdrawing the hot enriched gases from the still, and cooling them to recover condensable oils.

6. In the operation of the by-product recovery system of a coal distillation plantfthe process which comprises collecting hot fresh coal distillation gases from a part of the plant and tar to produce a hot pitch residuecontaining.

volatile oils, collecting hot freshooal distillation gases from av second part of the plant and'introducing them while yet at a temperature above 350 C. into a still, introducing the hot pitch residue into the still into direct lcontact with the hot gases therein, regulating the volume and contact of the pitch with the gases so that the pitch is heated to at least 125 C. and volatile oils are distilled therefrom, and the gases are partly cooled and enriched to at least twice their original'oil vapor content, simultaneously flushing the entire surfaces in the still exposed to the gases at said high temperature so as to provide thereon a continuously movingA iilm of the pit-ch being distilled, withdrawing thefhot enriched gases from the still, and cooling them separately from .the gases from which tar was recovered so as to separately condense oils therefrom. f

'7. The method of distilling a material of the comprises collecting and mingling in an insulated group consisting of tar, tarry oil, and pitch, which header hot fresh coal distillation gases from a Y comprises introducing hot fresh coaladistillation plurality of individual ovens or` retorts, the gases while yet at a temperature above 350 C. charges of which are at substantially different into a still, introducing the material into the ages, introducing these hot fresh coal distillation still into direct contact with the hot gases theregases while at a temperature above 350 C. into in, regulating the volume and contact of the a still, introducing a material of the group conmaterial with the gases so that the gasesy are sisting of tar, tarry' oil, and pitch into direct cooled to a temperature not less than 150 C. contact with the hot gases therein, regulating and the material is heated to at least 125 C. the contact of the material with 'the gases so b5 whereby volatile oils are distilled off from the that the material is'heated to at least 125 C. material and the gases are enriched to at least and volatile oils are distilled off therefrom and twice their original oil vapor content, simultathe gases arel only partly cooled and are enneously flushing the entire surfaces in the still riched to at least twice their original oil vapor exposed to the gases at said high temperature content, simultaneously flushing the entire surso as to maintain thereon a continuously moving faces'in the still exposed to the gases at said film of the material being distilled, withdrawing high,temperature so as te maintain thereon a the gases from the still, and cooling them to continuously moving film of the material being condense oils therefrom. distilled.

8. In the operation of the by-product recovery 11. In the operation of the by-product recov-l A system of ra coal distillation plant the process ery system of a coal distillation plant involving which comprises collecting, one part of the hot a plurality of ovens or retorts, the method which fresh coal distillation gases from the plant and' comprises collecting' and mingling hot fresh coal cooling them to separate tar containing pitch distillation. gasesifrom a plurality of individual constituents, collecting a second part of the hot Ovens or retorts, the charges of which are at fresh coal distillation gases from the plant and substantially different ages, introducing these hot introducing them into a still while yet at a temfresh coal distillation gases while yet at a temperature above 350 C., introducing into the still perature above 350 C. into a still, collecting hot into direct contact with the hot gases therein a fresh coal distillation gases from other ovens or material of the group consisting of tar,v tarry retorts and cooling them and recovering tar oil, and pitch containing the aforesaid pitch contherefrom, introducing the tar into direct constituents, regulating the volume of the material tact with the hot gases in the still, regulating the and the contact of the material with the gases contact of the material with/the gases so that the so that the gases are cooled to a temperature material is heated to at least 125-C. and ,vola-tile not less than 150 C. and the material is heated oils are distilled oif therefrom and the gases are t0 at least 125 C. whereby volatile oils are disonly partly cooled and are enriched to at least tilled from the material and the gases are entwice their original-oil vapor content, simultaneriched to at least twice their original oil vapor ously fiushing the entire surfaces in the still excontent, simultaneously flushing the entire surposed to the gases at said high temperature so as faces in the still exposed to the gases at said to maintain thereon a continuously movingilm high temperature so as to maintain thereon a` of the material being distilled, withdrawing the continuously moving lm of the material being hot enriched gases from the still and cooling them distilled,'withdrawing the hot enriched gases apart from the aforesaid coal distillation gases from the still, and cooling them apart from the from which tar is recovered so as to recover conaforesaid one part of the coal distillation gases densable oilstherefrom. so as to recover condensable oils therefrom. 12. In the operation of the by-product recov- 9. In the operation of the by-product recovery ery system of a coal distillation plant involv' gfx I system of a coal distillation plant theprocess a plurality of ovens or retorts, the method whic which comprises collecting one part of the hot comprises collecting and mingling hot fresh coal fresh coal distillation gases from the plant and distillation gases from a plurality of ovens or recooling them to separate tar containing pitch torts, the charges of which are at substantially constituents, collecting a.second part of the hot different ages, introducing these hot fresh coal fresh coal distillation gases and introducing them `.distillation gases while yet at a temperature into a still while yet at a temperature above above 350 C. into a still, introducing into the 400 C., introducing into the still into direct constill a material of the group consisting of tar, tact with the hot gases therein' a material 7of tarry oil, and pitch, and maintaining in the still the group consisting of tar, tarry oil/and pitch a liquid body of the material, withdrawing matecontaining the aforesaid pitch constituents, regurrial from the body thereof and 'bringing it into lating the volume of the material andthe conintimate contact with the hot gases in the still, tact of the material with the gases so that the regulating the contact of the material with the material is heated to. at least 125 C. and volatile gases so that the material is heated to at least oils are distilled therefrom, and the gases are 125 C. and volatile oils are distilled off therecooled within two seconds of their entry into from and the gases are only partly cooled and ycon'tact'with the material to a temperature below are enriched to at leastv twice their original oil 400 C., simultaneously flushing the entire survapor/content, simultaneously flushing the entire 3,40 faces in the still exposed to the gases at said surfaces in the still exposed to the gases at said high temperature so as to maintain thereon a high temperature so as to maintain thereon a continuously moving lm of the material being continuously moving lm of the material being distilled, withdrawing the h'ot enriched gases distilled, withdrawing the hot enriched gases from from the still, and cooling themfapart from the the stilland cooling them to condense oils thereaforesaid one part of the coaldistillation` gases from. ,so as to recover condensable oils therefrom. 13. The methodof distilling a material of the 10. In theoperation of the by-product recovery group consisting of tar, tarry oil, and pitch which systemofy a coal.distillation plant involving a comprises introducing hot fresh coal distillation I plurality of ovens or retorts, the method which 'gases while yet at a temperature above 350 C. 150

into a still insulated against heat loss, introducing the material into direct contact with the hot gases in the still at a rate not exceeding 20 gallons per 1000 cubic feet of gas whereby the material is heated to at least, 125 C.-and is distilled and the gases are only partly cooled and are enriched to at least twice their original oil vapor content. and simultaneouslyushing the entire surfaces in the still exposed to the gases at said high ternperature so as tomaintain thereton a continuously moving liquid film. l

14. The methodA of distilling tar to produce pitch and distillate oil, which comprise distilling off from the'tar a portion of the volatile oils contained therein so as to form a hot residue still containing volatile oils, introducing hot fresh coal distillation gases while yet at a temperature above 350 C. into a still, introducing the hot residue intothe still into direct contact with the hot gases therein, regulating the volume and contact of said residue with the gases so that the residue is heated to at least 125 C. and volatile oils are distilled therefrom and the hot gases are partly cooled and enriched to at least twice their original oil vapor content, simultaneously flushing the entire surfaces in the stillexposed to the gases at said high temperature so as to maintain thereon a continuously moving lm of the material being distilled, withdrawing theY hot enriched gases from the still and bringing them into heat exchange relation with the tar to preheat it, and then further cooling them to recover condensable oils.

l5. In the operation of the by-product recovery system of a coal distillation plant involving a plurality of ovens `or retorts, the method which comprises collecting and mingling hot fresh coal distillation gases vfrom a plurality of individual ovens or retorts containing charges of different ages, introducing these hot fresh coal distillation gases while yet at a temperature above 350C. into a still, collecting hot fresh coal` distillation gases from other ovens or retorts and cooling them and recovering tar therefrom, introducing the tar into'the still and maintaining a liquid body of the tar and distillation residue therein, withdrawing tar from the body thereof and bringing it into'intimate contact with the gases in the still so that the tar-is heated to at least 125 C. and vvolatile oils are distilled olf therefrom and the gases are only partly cooled and are enriched to at least twice their original oil vapor content, simultaneously flushing the entire sur,- facesin the still exposed to the gases at said high temperature so as to maintain thereon a continuously moving film of the material being distilled, withdrawing the hot enriched gases from the still and cooling them apart from 'the coal distillation gases from which tar is recovered so as to recover f condensable oils therefrom.

' tion gases from other ovens or retorts and cooling them and recovering tar therefrom, introducing the -tar into the still and maintaining therein a body of the tar of such depth that said revolving paddle elements dip therein, repeatedly spraying the tar into the gases by rapidly revolving the spray. paddles, the axis of revolution being substantially parallel to the surface of the body of tar, controlling the speed of revolution of the paddle elements and the introduction of the tar so that the tar is heated to at least 125 C. and volatile oils are distilled off therefrom and the gases are only partly cooled and are enriched to at least twice their original oil vapor content, and the entire surfaces in the still exposed to the gases at said high temperature are continuously flushed with a continuously moving film of the material being distilled, withdrawing the hot enriched gases from the still, and cooling' them apart from the coal distillation gases from which tar is recovered so as to recover condensable oils therefrom.

1'7.l In the operation of the by-product recovery system of a coal distillation plant involving a plurality of ovens or retorts, the method whichl comprises collecting and mingling hot fresh coal distillation gases from a plurality of individual ovens or retorts having charges of different ages, introducing these hot fresh coal distillation gases while yetv at a temperature above 350 C. into a still having a' plurality of rapidly rotating discs, collecting hot fresh coal distillation gases from other ovens or retorts and cooling them and recovering tar therefrom, introducing tar into the still and maintaining a body thereof in the still of such depth that said rotating discs contact therewith, repeatedly spraying the material being distilled into the gases by rapidly rotating the discs, regulating the rotation of the discs and the introduction of the tar so that the tar is heated to at least 150 C. and 'volatile oils are distilled off 11D ture are flushed with a continuously moving lm 1 18. In the operation of the by-product recovery vsystem of a coal distillation plant involving a plurality of ovens or retorts, the method which comprises collecting and mingling hot fresh coall distillation gases from a plurality of individual ovens or retorts, having charges of different ages, introducing these hot fresh coal distillation gases while yetf at a temperature above 350 C. into a tower still and passing them therethrough,

spraying a material of the 'group consisting of tar, 3

tarry oil, and pitch through the hot gases passing through the tower still, regulating the contact of the material with the gases so that the material is--heated to at least C. and volatile oils are distilled offtherefrom and the gases are only partly cooled and` are enriched to at least twice their original oil vapor content, simultaneously flushing entire surfaces in the still exposed to the gases at said high temperature so as to maintain thereon a continuously moving film of the material being distilled, withdrawing the hot enriched gases from the still, and cooling them to recover condensable oils therefrom.

19. In the operation of the by-product recovery system of a coal distillation plant involvingl a plurality of ovens or retorts, the method which comprises collectingiand mingling hot fresh coal distillation gases from a plurality of individual ovens or retorts having charges of different ages,

introducing these hot fresh coal distillation gases .generally cocurrent direction therewith, regulating the contact of the tar with the gases so that the tar is heated to at least 150 C. and volatile oils are distilled off therefrom andthe gases are only partly cooled and are enriched to at least twice their originalcil vapor content, simultaco I neously flushing the entire surfaces in the still `exposed to the gases at said high temperature .so as to maintain thereon a continuously moving ilm of the material being distilled, withdrawing the hot enriched gases from the still and cooling them to recover oils therefrom.

20. In the operation of the by-product recovery system of a coal distillation plant involving a plurality of ovens or retorts, the method which comprises collecting and mingling-hot fresh coal distillation gases from a pluralityr of individual ovens or retorts, the charges of which are at substantially diiferent ages, introducing these hot fresh coal distillation gases'whileyet at a temperature above 350 C. into, a still and passing them therethrough, collecting hot fresh coal distillation gases from other vovens or retorts :and cooling them and recovering tar therefrom, introducing thevtar into direct countercurrent contact with the hot gases leaving vthe still thereby distilling off a part of the volatile oils from the tar, spraying the hot partly distilled tar through ,the gases passing through the still in a generally cocurrent direction therewith and regulating the spray of tar so that the tar is heated to at least 125 C. and volatile oils are distilled therefrom and the gases are only partly cooled and are enriched to at least twice their original oil vapor content, simultaneously flushing the entire surfaces in the still exposed to the gases at said high temperature so as to maintain thereon a continuously moving lm of the tar being distilled, removing the hot gases from the still and, after passing them in countercurrent contact with the "ingoing' tar, cooling them apart from the aforesaid coal distillation gases from which tar is recovered so asto separately recover condensable oils therefrom.

21. The method of distilling a liquid hydrocarbon by direct contact with high temperature gases, which comprises continuously introducing into a still the high temperature gases and the' liquid hydrocarbon to be distilled, continuously removing from the still the gases and admiXed hydrocarbon vapors and undistilled residue and effecting distillation of the hydrocarbon by the gases by causing the hydrocarbon to circulate rapidly as a liquid over the interior walls of the still and by spraying the hydrocarbon into the gases, whereby the gases pass through a conduit of the liquid hydrocarbon filled with spray of the hydrocarbon, and whereby the gases are almost instantly cooled to a temperature' approaching the temperature of the vhydrocarbon and the hydrocarbon is rapidly distilled by contact with the gases.

22. The method of distilling a liquid hydrocarbon by direct contact with high temperature gases, which comprises continuously maintaining a rapidly changing conduit of the liquid hydrocarbon lled with an intense spray of the hydrocarbon, and passing the high temperature gases through such conduit in intimate contact with" the hydrocarbon.

STUART PARMELEE MILLER. 

